1. Field of the Invention
The present invention relates to: a cyan ink containing a water-insoluble coloring material; and an ink set having the same. More specifically, the present invention relates to a cyan ink suitable for an ink-jet recording method.
2. Related Background Art
Ink containing, as a coloring agent, a water-insoluble coloring material such as a pigment (pigment ink) has been conventionally known to provide an image excellent in fastness such as water resistance and light resistance. Various techniques have been recently proposed for the purpose of increasing the image density of an image formed by means of such ink.
For example, there has been proposed the use of ink containing self-dispersion carbon black and a specific salt to achieve an additional increase in image density (see, for example, Japanese Patent Application Laid-open No. 2000-198955). A technique has also been proposed, which involves: causing ink-jet recording ink, which is a composition containing a pigment, polymer fine particles, a water-soluble organic solvent, and water, and a polyvalent metal salt-containing aqueous solution to adhere to a recording medium; and causing the ink composition and the polyvalent metal salt-containing aqueous solution to react with each other to form a high-quality image (see, for example, Japanese Patent Application Laid-open No. 2000-63719). In each of those techniques, a pigment present in ink in a dispersed state is forcedly flocculated at the surface of a recording medium to suppress the permeation of the pigment into the recording medium, thereby obtaining an image with an increased density.
In addition, pigment ink causes a pigment to flocculate on a recording medium, so the pigment is apt to remain on the surface of the recording medium. In particular, when printing is performed on plain paper by means of pigment ink that does not contain any resin or the like, a pigment particle itself remains on the surface of the recording medium. As a result, even after a sufficient time period from the printing, an image may be contaminated when the image is strongly scratched.